Aeronautical propeller



Ap 1, 1941. P. J. GATHMANN AERONA UTICAL PROPELLER Filed June 14, 1938 5Sheets-Sheet l IN VENTOR Zmazzrz.

ATTORNEY P. v.1. GATHMANN 2,237,030

April 1941.

April 1, 1941. v P. J. GATHMANN AERONAUTIOAL PROPELLER Filed June 14,1938 5 Sheets-Sheet 3 APril 1941- P. J. GATHMANN 2,237,030

AERONAUTICAL PROPELLER Filed June 14, 1938 5 Sheets-Sheet 5 PatentedApr. 1 1941 UNITED STATES PATENT OFFICE azsipso A ,AERQNAUTICALPROPELLER Paul J. Gathmann, Lombard, 111. Application June 14, 1938,Serial No. 213,646 7 Claims. (01. 170-162) This invention relates tocertain improvements n aeronautical propellers. One object of theinvention is the provision of relatively simple and automaticallyoperative means for changing the angular pitch of the propeller bladesin response to changes of engine speed. Another object is to arrangesuch automatic mechanism for actuation by centrifugal force duringrotation of the propeller. Further objects and the specific n-a e of theinvention will be readily recognized oy those skilled description andexplanation, panying drawmgs illustrating certain embodiments thereof;that various modifications and re-arrangements of the features andelements may be made without departing from the spirit and scope of theinvention, and that I do not limit myself to the ticular forms andcombinations herein shown, except as indicated by the accompanyingclaims.

the drawings:

Figure l is a front elevation of an aeronautical propeller with the hubcover plate removed, and with parts shown in section to reveal certaindetails of construction.

Figure 2 is a transverse section of the propelle'r taken substantiallyat the plane of the axis of the drive shaft and through the intersectingaxis of one propeller blade.

Figure 3 is a section taken transversely through a propeller blade, andindicating its range of adjustment with respect to the plane of rotationfor and from the accompreferred relatively low engine speeds.

Figure 4 is a similar section through a propeller blade indicating therange of angular adjustment employed at normal engine speeds in flying.I

Figure 5 is also a section through a propeller blade showing itsadjustment transversely of the plane of rotation .to serve as a paddlewheel resistance or brake to prevent racing of the engine.

Figure 6 is a transverse detail section taken as indicated at line '6-6on Figure 2.

in in the art, froni the following Figure 12 is a. detail section takentransversely of the drive shaft and looking into the front cover plate.v

Figure 13 is a front elevation of the central portion of the propellershowing the cover plate in position.

Figure 14 is a transaxi-al view of the hub portion.

of a propeller embodying the modification of the invention.

Figure 15 is a section taken as indicated at line 15-45 on Figure 14.

Y the weights of Figure 14.

but it should be understood Figure '7 is a transverse section taken asindicated at line 1-4 .on Figure 2.

Figure 8 is a detail section showing the centrifugally operated weightsand their inter-connection through a crank plate.

Figure 9 is an edge view of the crank plate.

Figure 10 is a detail section on a. larger scale showing one of theweights and being taken substantially as indicated at line lO-Hl onFigure 8.

Figure 11 is a detail section on an enlarged scale showing one of thesynchronizing pinions and its control spring.

Referring first to Figures 1 and 2, it will be seen that the structuretherein illustrated includes a chambered hub housing l0, supporting aplurality of radially disposed propeller blades, preferably of metallicmaterial, and'each mounted for easy rotative adjustment about'its ownaxis in bearings formed in the radial branches of the housing H), withshoulders l2 and I3 arranged to receive the radial thrust of the bladesdue to centrifugal force. The hubhousing I0 is fixedly keyed to thepropeller drive shaft 14, as by splines HI, and M and is held in placeon the shaft by a retaining nut l5 screwed onto the outer end of theshaft, as seen in Figure 2. V

Each of the propeller blades H terminates at its root end in a hollowshank I l having on its inner surface a plurality of helical grooves I6.

As illustrated, the propeller is provided with three blades, and thehollow shanks of these blades contain automatic controlling weights t8,I9 and 20 respectively, each formed with helical ribs or splines ofsuitable pitch and dimensions to intermember with the helical grooves inthe hollow propeller shanks. Thus, in response to centrifugal "forcegenerated by rotation of the propeller about the axis of its drive shaftI4, the weights t8, l9

and 20 tend to move radially outward in. the

shanks of the respective propeller blades, and if the weights berestrain-ed against rotation, their movement will tend to producerotative adjust.- ment of the propeller blades by virtue of theinterengagement of the helical grooves and splines.

As seen in Figure 8, the weights l8, l9 and 2D constitute a unitaryassembly by virtue of their connection to a crank plate 2| which ismounted for free oscillatory movement upon the propeller shaft l4 and isformed withrecesses 22, 23 and 24 in its periphery. These recessesrespectively accommodate the connecting torque rods 25, l6v and 21, eachhaving one end attached to the crank plate 2| by means of a pivot pin 21At their opposite ends the rods are connected to the respective weightsby pivots I 3 I9 and 2|] which extend through recesses I 8 I!! and 20 inwhich the ends of the rods are accommodated similar and equal movementof the other weights, I and any tendency to inequality in such movementsas might result from difierences of friction' or otherwise, will beintegrated and equalized by this inter-connection of the weights to thecrank plate 2|. At the same time, the connect ing rods 25, 26 and 21,being of rectangular crosssection and fitting snugly between theparallel cheeks 9f the recesses 22, 23 and 24, and the cheeks of therecesses l8 N and 20 operate as torque members to prevent twisting orrotatlve movement of the weights, thus insuring that their radial travelwill cause rotative adjustment of the propeller blades.

Each of the propeller blade shanks II- is provided at its root end witha mitre gear 28 extending well into the hub housing It), and thesegears, in turn,..mesh with synchronizing pinions 29 journaled in thewall of the housing, as seen in Figure 1. a

The front side ofthe hub housing In is provided with a removable coverplate 3| within lar 43 on the stub shaft. Thus any rotativ'e adjustmentof the propeller blades, causing corresponding rotation of the pinions29, inter-meshing with the mitre gears 28, takes place in thepresence ofsome tension in the springs 46, which serve to take up any possibleback-lash in the connections, insuring smooth, even movement throughoutthe range of adjustment, and avoiding vibration of the parts withrespect to each other. Maintaining this' spring tension and operating inopposition to it at all times is the centrifugal force created in theweights l8, I9 and 20 by the rotation'of the propeller assembly.

The retractor spring 35 operates in the-. ,same

direction as the springs 46, so that all the springs work together toprevent looseness or vibration in theoperationpf the automatic adjustingfeatures. And in order to effect a still more perfect synchronization ofthe parts I may provide aring gear 50, which is formed as a mitre gearand is shown in Figure 2 as rotatively mounted on the internal hubportion l0 of the rear bearing of the hub housing so as to mesh with thethree mitre gears 28, but not with pinions, 29.

which there is enclosed a worm 32 and a worm wheel 33 meshing therewith,as best seen in' Figures 2 and 12. The worm wheel 33 has a central hubsleeve 34 suitably bored to fit loosely upon the propeller shaft I4,- topermit of easy rotative adjustment by operation of the worm 32. Suchadjustment may be eifected by means of a" suitable tool, such as asocket wrench, engaging the squared end 32 of the shaft of the worm 32,which is accessible through an opening 3 I in the cover plate 3| ,asseen in Figure-13.

To provide a balancing eifect and prevent back-lash or vibration duringrotative adjust '35 is thus adjustable by means of the worm 32.

The transverse surface 33 of a recess 33 in the cover plate 3| serves asa thrust bearing to accurately position the worm wheel 33 in alignmentwith its worm 32, while the hub sleeve 34 extends into abutment with onehub of the crank plate v 2|, the other hub of the crank plate beingfitted against the inner end surface 2| of the rear hub bearing so thatthe crank plate 2| is maintained in proper relation to the common planeof the propeller blade axes.

Referring again to the synchronizing pinions 29, it may be noted thatthey'are mounted for easy turning in the bearing blocks 40, which aresuitably threaded to be screwed into position in threaded openings ofthe hub housing l0, Each of the pinions 29 has a stub shaft 4|protruding through the bearing block and terminating out.- wardly inashort, square'shank 42, upon which. there is'mounted a collar, 43,having asquare hole 43 by which' it engages the shank 42 for; turningtherewith. A retaining nut 45 holds the collar in place.- A retractingspring 46 is shown coiled around a protruding portion of the bearingblock 40 and the outer end of the stub shaft,

- with one end of the spring anchored to the bear- -ing block and theother end secured to the col- It should be understood that. in thedrawings the parts of the invention are shown in the positions whichthey occupy when the propeller is not in operation, the'weights l8, l9and 20 being shown at their innermost limiting positions nearest theaxis of the shaft l4, from which positions they wi11 gradually moveoutwardly under the influence of the centrifugal force generated byrotation of the propeller. -With the parts in the positions indicated,the retracting springs and their bearings and in opposition to thetension 46 are at minimum tension, but as the propeller revolves, theweights, being held against rotation by ,virtue ofwtheir engagement withthe torque rods 25, 26 and 21 and the crank plate 2|, will travelradially outward, causing the hollow shanks ll of the/propeller blades,to-turn in of the springs 46, acting through the mitre pinions 29, andto the tension of the spring 35 tending to resist rotation of the crankplate 2|. Thusthe centrifugal force is balanced againstthese variablespring tensions to insure smooth action and a definite position of eachpart throughout the range of adjustment.

The parts are all substantially symmetrical in their arrangc'ment aboutthe axis of revolution, so that the perfect balance of the propeller ismain-' tained for all speeds,

Figures 14 and-l5 illustrate a modification of the'structure, andalthough, in these views, the propeller is shown as having only twoblades, it should be understood that this form of the invention isequally applicable to a propeller. of three blades, such, for example,as that shown in Figures 1 to 13. In this form the hub housing A issecured by means of splines B to the drive shaft C for rotating thepropeller as an entirety. Securely fastened to the shaft C within thehub. hou,sing'A is a block-like sleeve D; if desired, the splines B mayextend into the block to secure it firmly to the shaft 0 for-rotationtherewith. The block D carries radially extending torque rods E, E, eachof which is of square cross-section, and which may be made integral,with the block D. v

The hub housing A includes suitable bearings ,A in which the hollowshanks of the propeller blades A are mounted for easy rotativeadjustment. The inner wall of thehollow shank of each propeller blade isformed with a plurality of helical grooves E which register with andengage shanks to synchronize and equalize the helical splines Gextending-from the pitchchange governorweights' H. These weights arepreferably cup-shaped, as indicated in dotted outline on Figure 14, andas more clearly seen in Figure 15, each having a centrally upstandinghub portion J formed with a square bore K by which the weight isslidably' guided on the square torque rod E for radial movement thereon.At the outer extremity of each torque rod there is secured a shoulderednut L, the extreme end of the rod being threaded to receivethe nut. And

interposed between the nut L and the transverse end wall of thecup-shaped weight H there is provided' a coil spring M which normallyholds the weight seated against the block D, "as shown in Figure 14, andtends to yieldingly oppose its radial movement outward in response tocentrifugal force when the propeller revolves.

In order that the propeller blades shall be equally adjusted at alltimes, they are shown inter-connected by bevel gears P secured to theroot end of each propeller blade inside the hub housing A and meshingwith bevel pinions Q and R, which are loosely mounted upon the driveshaft 0.

Referring to Figures 3, 4 and 5, it should be understood that the arrowX in each instance'indicates the direction of rotation of the propeller.In Figure 3 the angle a at which the propeller blade II is shownadjusted, represents the initial position of the blade when at rest. OnFigure 4 the angle b indicates the range of adjustment through which theblade may be shifted as the speed increases, the limiting angle shown asapproximately 45 degrees corresponding to optimum pitch for fullefiiciency. Any further movement of the governor weights caused by anincrease in the centrifugal force acting upon them, such increase being,in turn, caused by added velocity of rotation of the propeller, will iinto the angular range 5, which is to be considered as the maximum orover-revving setting of the propeller blades at which they offerpaddle-wheel resistance, so that the propeller becomes a governor forholding the engine to its maximum intended speed.

In both forms of the invention illustrated herein the pitch of thehelical features which intend to shift the blades l indicated at c inFigure terconnect the weights and the hollow shanks of the propellerblades is such that the wind resistance against the blades cannot turnthem; in other words, the helical drive between the weights and theblades is irreversible. Thus the blades are held firmly at all positionsof adjustment.

I claim:

1. In a variable pitch propeller, a hub and a plurality of bladescarried thereby, each blade having a closed hollow shank mounted in thehub for rotation about its own axis, weights guided for movementrespectively within said hollow shanks in response to centrifugal forcewhen the propeller revolves, said weights and the inner surfaces of thehollow shanks having inter-engaging helical features, the weights beingrestrained against rotation whereby the movement of the weights alongthe shank axes tends to cause'rotative adjustment of the propellerblades, a crank plate journaled within the hub, and substantiallystraight links connecting said crank plate with said weightsrespectively to insure equal and simultaneous movements of the weightsalong the respectiveaxes of the blade propeller revolves, each of mentof the blades, and a torsion spring yieldingly connecting the plate tothe hub and opposing rotation of the plate in response to the action ofcentrifugal force on said weights.

2. In the combination defined in claim 1, pivotal meansv connecting oneend of each of said links to the crank plate and pivotal meansconnecting the other endof each link to one of the weights, the link andsaid connections serving as the means for restraining the weight againstrotation "about the axis of the propeller blade shank.

3. In a .variable pitch propeller, a. hub and a plurality of bladescarried thereby, each blade having a hollow shank mounted in the hub forrotation about its own axis, a weight guided for movement within saidhollow shank and along its axis in response to centrifugal force whenthe said hollow shanks having a gear rigidly secured to its inner endwithin the hub, pinions inter-meshing with said gears and connectingthem for simultaneous and equal rotation, each of the weights and theinner surface of the shank in which it moves having inter-engaginghelical features, and means extending from the hub and restraining theweight against rotation whereby its movement along the axis of the shankserves-to cause rotative adjustment of the propeller blade, togetherwith separate spring means associated with each of said pinions andyieldingly resisting rotation thereof to prevent back-lash in the gearconnections when the blade shanks are rotated.

4; In a variable pitch propeller, a shaft, a hub mounted on said shaftand a plurality of blades carried by the hub, each blade having a hollowshank mounted in the hub for rotation about its own axis, a weightguided for movement within said hollow shank and along .its axis inresponse to centrifugal force when the propeller revolves, means wherebysuch centrifugally induced movement of the weight produces rotativeadjustment of the shank of the blade in which it travels, a platerotatably mounted within the hub connected to,the several weights in theblade shanks for rotation in response to their movements within saidshanks, and a spring coiled about the the adjust- 75 tively to saidplate and said hub to resist rotation of the plate and movement of-theweights outwardly within the shanks of theblades and serving to retractthe weights inwardly as the speed of revolution of the propeller isreduced.

5; In the combination defined in claim 4, means for adjusting theinitial tension of said spring at will and accessible from the outsideof the hub.

6. In a variable pitch propeller, a hub and a plurality of bladescarried thereby, each blade having a hollow shank mounted in the hub forrotation about its own axis, and a weight guided for movement withinsaid hollow shank and along its axis in response to centrifugal forcewhen the propeller revolves, said weight and the extenda simultaneousrotative adjustments of the'propeller blades, spring means opposing themove-.

hub, a shaft to which said hub is secured, said hub including aplurality of blade bearings, blades having hollow shanks rotatablymounted in said bearings respectively, a weight guided in each shank forradial movement therein in response to centrifugal forceduringrevolution of the propeller, said weights and the inner surfacesof said shanks having inter-engaging helical featuresa rotatably mountedcrank plate coaxial with the shaft, links connecting said crank plate tothe weights respectively, said weights being restrained against rotationabout the axes of the i respective blade shanks whereby theirradialmovement causes rotation of the shanks and their associatedblades, and a spring coiled about the axis of said shaft having one endconnected to said crank plate and the other end connected with said hubfor yieldingly restricting rotation of the crank plate and correspondingmovement of the weights upwardlywithin the shanks of the blades andserving to retract said weights in-' wardly as the speed of revolutionof the propeller is reduced.

PAUL J. GATHMIANN.

CERTIFICATE OF coRREcTIo1 7 Patent No. 2,257,050. April 1,

PAUL J. 'GATHMANN.

It is, hereby certified that error appears in the above numbered patentrequiring correction as follows: In the drawing, strike out sheets 1,'2, and L and insert instead the following and that the said LettersPatent should be read with this correction therein that the same may.conform to the-record of the case in the Patent Office- Signed andsealed this 11th day of November, A. D. 19141.

Henry Van Arsdale,

(Seal) Acting Commissioner of Patents.

P 1 P. J. GATHMANN AERQNAUTICAL PROPELLER Filegi'J'une 14, 1938 5 Sheets-Shpet l INVENTORI.

-- ai/zmalzn,

ATTORNEY.

April 1, 1941. P. J. GATHMANN AEBOHA-UTICAL PRO PELLER Filed June 14,1938 5 Sheets-Sheet 2 ORNEY April 1941- P. J. GATHMANN 2. 37.030

AERONAUTICAL menu. 7

5 Sheets-Sheet 4 mvsmm. BY P Z J 6575722017? v S a:

' ATTORNEY.

